In cutting wood, plastic or metals with a router or shaper, the workpiece is moved past cutter blades rotatably mounted on a vertical shaft. As practised in the prior art, this operation is inherently dangerous, especially when narrow molding pieces must be machined, because the worker has to hold the workpiece as it is being moved past the cutter blades. Generally, the less shoulder height a workpiece has, the closer a user""s hands tend to be to the blades. The potential for serious injury jumps dramatically in those cases in which that portion of the workpiece used as a guide surface defines, once the workpiece has been cut, only a very narrow shoulder. To overcome these hazards, special holding fixtures, custom-designed for each job, have been used in the prior art.
The object of the present invention is to provide a device which can be installed quickly and used to hold a workpiece in a safe manner, regardless of the cuts made upon it, so that longstanding needs in the art of shaping can be met.
It is a further object of this invention to provide such a device which is relatively inexpensive to manufacture and which can be used to improve the competitive edge of small production shops.
In accordance with the present invention, there is provided at least two holding arms including a pair of rubber-faced rollers, each roller being rotatably mounted on a vertical shaft held above a shaper table. Spaced apart from each other, the rollers are used to hold an elongated workpiece against the table""s guide fence.
Means for adjusting the position of each roller relative to the guide fence includes at least one elongated solid metal rod and a post in which the rod, once it has been slip-fitted therein, is held in a horizontally extended position above the shaper table. Sized to have a length in excess of the transverse width of the shaper table, the rod defines a forked end to which is rigidly attached a yoke for supporting the roller shaft. In the preferred embodiment, the metal rod, in tranverse cross-section, generally defines an imaginary square.
The post itself terminates downwardly in a foot which is slideably mounted on a track which defines a tee slot. Affixed to the shaper table, the track is secured thereto in such a way that the tee slot runs approximately parallel to the longitudinal centerline of the guide fence.
Posts can be individually moved along the track and then locked in place prior to use. Moreover, a table setup can be provided in which more than one set of shaper blades are arrayed in a sequence; and additional arms, whose posts are anchored in the same tee slot, hold the workpiece before and after each set. The locking means used to hold each post in place relative to the track is a pinch bolt which presses the foot of the post against portions thereof defining the top edges of the tee slot.
A spring-actuated locking means secured to each post prevents the respective arm held therein from moving, once the horizontal extension of the arm has been set, relative to the post. The locking means includes, in addition to the spring, at least one clutch plate encircling the rod held in that particular post. The spring, when compressed, allows the rod to be slid backward relative to the workpiece; when released, the spring presses edges of the clutch plate against the rod, locking it in position. However, the clutch plate allows the rod to be slid forward without compressing the spring. The end of the rod distal from the roller terminates in a handle which the user can grasp to facilitate sliding the rod relative to the post, as well as to move the post along the track.
In most applications, two holding arms according to the present invention are adequate for holding a workpiece as it is being machined by a shaper. Initially, the rubber-faced roller on the first arm is used to press an uncut portion of the workpiece against the shaper fence. As soon as the workpiece has been moved past the shaper blades, the rubber-faced roller on the second arm is advanced until it pushes a cut section of the workpiece against the guide fence. The position of the second rubber-faced roller can be adjusted in seconds to accommodate cut sections having different shapes.
The applicant has used the present invention in his own small production shop with great success.